Coatings Challenges in Harsh Environments

A special issue of Coatings (ISSN 2079-6412).

Deadline for manuscript submissions: closed (10 November 2021) | Viewed by 18790

Special Issue Editor


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Guest Editor
1. TWI, Granta Park, Cambridge CB21 6AL, UK
2. Materials Innovation Centre, School of Engineering, University of Leicester, Leicester LE1 7RH, UK
Interests: corrosion; coatings; electrochemistry; thermal spraying
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Special Issue Information

Dear Colleagues,

Harsh environments are encountered in several industries around the world. These environments vary greatly from the extremes of temperature and pressure to that of corrosive fluids. To remain operational, the industrial components need to retain their useful properties in such harsh environments.

Protective coatings often allow process equipment to be purposeful in environments well beyond the operational limit of comparable uncoated components. Durability, ease of application, repairability, reliability and long-term performance are vital characteristics of such coatings. The overall cost effectiveness of these coatings is key to their industrial uptake. Therefore, this Special Issue of Coatings entitled “Coatings Challenges in Harsh Environments” is devoted to research and review articles on the metallic, non-metallic and composite coatings used in aggressive environments.

In particular, the topics of interest include, but are not limited to:

  • Coatings for high temperature and molten salt applications;
  • Coatings for mitigating corrosion in CO2 and H2S environments;
  • Thermal spray and cold spray coatings for aggressive environments;
  • Corrosion, wear and cavitation resistant coatings;
  • Coatings for mitigating marine corrosion;
  • Coatings for nuclear applications;
  • Coatings for chemical and petrochemical plants;
  • Coatings for aeroengine turbines, such as thermal barrier coatings;
  • Coatings for applications in space;
  • Coatings for oil sands and other oil and gas exploration environments;
  • Coatings for applications in geothermal environments.

Dr. Shiladitya Paul
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Coatings is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

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Published Papers (4 papers)

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Research

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16 pages, 6112 KiB  
Article
The Effect of Polytetrafluoroethylene (PTFE) Particles on Microstructural and Tribological Properties of Electroless Ni-P+PTFE Duplex Coatings Developed for Geothermal Applications
by Gifty Oppong Boakye, Arna María Ormsdóttir, Baldur Geir Gunnarsson, Sandeep Irukuvarghula, Raja Khan and Sigrún Nanna Karlsdóttir
Coatings 2021, 11(6), 670; https://doi.org/10.3390/coatings11060670 - 01 Jun 2021
Cited by 14 | Viewed by 4308
Abstract
The selection of electroless nickel-phosphorus plating (ENP) has been inclined towards their properties and advantages with complex geometry applications. These properties include coating uniformity, low surface roughness, low wettability, high hardness, lubricity, and corrosion- and wear-resistance. Materials used in geothermal environments are exposed [...] Read more.
The selection of electroless nickel-phosphorus plating (ENP) has been inclined towards their properties and advantages with complex geometry applications. These properties include coating uniformity, low surface roughness, low wettability, high hardness, lubricity, and corrosion- and wear-resistance. Materials used in geothermal environments are exposed to harsh conditions such as high loads, temperature, and corrosive fluids, causing corrosion, scaling, erosion and wear of components. To improve the corrosion- and wear-resistance and anti-scaling properties of materials for geothermal environment, a ENP duplex coating with PTFE nanoparticles was developed and deposited on mild steel within the H2020 EU Geo-Coat project. ENP thin adhesive layer and ENP+PTFE top functional layer form the duplex structure of the coating. The objective of this study was to test the mechanical and tribological properties of the developed ENP-PTFE coatings with varying PTFE content. The microstructural, mechanical and tribological properties of the as-deposited coating with increasing PTFE content in the top functional layer in the order: ENP1, ENP2 and ENP3 were evaluated. The results showed maximum wear protection of the substrates at the lowest load; however, increasing load and sliding cycles increased the wear rates, and 79% increased lubrication was recorded for the ENP2 duplex coating. The wear performance of ENP3 greatly improved with a wear resistance of 8.3 × 104 m/mm3 compared to 6.9 × 104 m/mm3 for ENP2 and 2.1 × 104 m/mm3 for ENP1. The results are applicable in developing low friction, hydrophobic or wear-resistive surfaces for geothermal application. Full article
(This article belongs to the Special Issue Coatings Challenges in Harsh Environments)
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18 pages, 6049 KiB  
Article
Study of Al2O3 Sol-Gel Coatings on X20Cr13 in Artificial North German Basin Geothermal Water at 150 °C
by Gabriela Aristia, Le Quynh Hoa, Marianne Nofz, Regine Sojref and Ralph Bäßler
Coatings 2021, 11(5), 526; https://doi.org/10.3390/coatings11050526 - 29 Apr 2021
Cited by 5 | Viewed by 1990
Abstract
Al2O3 has been widely used as a coating in industrial applications due to its excellent chemical and thermal resistance. Considering high temperatures and aggressive mediums exist in geothermal systems, Al2O3 can be a potential coating candidate to [...] Read more.
Al2O3 has been widely used as a coating in industrial applications due to its excellent chemical and thermal resistance. Considering high temperatures and aggressive mediums exist in geothermal systems, Al2O3 can be a potential coating candidate to protect steels in geothermal applications. In this study, γ-Al2O3 was used as a coating on martensitic steels by applying AlOOH sol followed by a heat treatment at 600 °C. To evaluate the coating application process, one-, two-, and three-layer coatings were tested in the artificial North German Basin (NGB), containing 166 g/L Cl, at 150 °C and 1 MPa for 168 h. To reveal the stability of the Al2O3 coating in NGB solution, three-layer coatings were used in exposure tests for 24, 168, 672, and 1296 h, followed by surface and cross-section characterization. SEM images show that the Al2O3 coating was stable up to 1296 h of exposure, where the outer layer mostly transformed into boehmite AlOOH with needle-like crystals dominating the surface. Closer analysis of cross-sections showed that the interface between each layer was affected in long-term exposure tests, which caused local delamination after 168 h of exposure. In separate experiments, electrochemical impedance spectroscopy (EIS) was performed at 150 °C to evaluate the changes of coatings within the first 24 h. Results showed that the most significant decrease in the impedance is within 6 h, which can be associated with the electrolyte penetration through the coating, followed by the formation of AlOOH. Here, results of both short-term EIS measurements (up to 24 h) and long-term exposure tests (up to 1296 h) are discussed. Full article
(This article belongs to the Special Issue Coatings Challenges in Harsh Environments)
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15 pages, 10361 KiB  
Article
Prediction of Thermal Spray Coatings Performance in Marine Environments by Combination of Laboratory and Field Tests
by Rosa Grinon-Echaniz, Shiladitya Paul, Rob Thornton, Philippe Refait, Marc Jeannin and Alvaro Rodriguez
Coatings 2021, 11(3), 320; https://doi.org/10.3390/coatings11030320 - 11 Mar 2021
Cited by 8 | Viewed by 3502
Abstract
Cost-effective corrosion mitigation of offshore steel structures can be achieved by thermal spray coatings. These coatings, when comprised of Al, Zn and their alloys, provide a physical barrier against the environment when intact, and cathodic protection to underlying steel when damaged. Due to [...] Read more.
Cost-effective corrosion mitigation of offshore steel structures can be achieved by thermal spray coatings. These coatings, when comprised of Al, Zn and their alloys, provide a physical barrier against the environment when intact, and cathodic protection to underlying steel when damaged. Due to the complexity of marine environments, laboratory tests should be combined with field work in order to understand the corrosion protection offered by these coatings. The work presented here was carried out with thermal spray coatings of aluminum alloys (AA1050, AA1100, Al-5Mg) and Zn-15Al prepared by Twin Wire Arc Spray onto low carbon steel substrates. The resulting coatings were ~300 μm in thickness, and 5% of surface area defects were artificially machined in order to expose the steel substrate, simulating mechanical damage or erosion of the coating. Electrochemical data collected over a 90 days period showed a good correlation between laboratory and real marine environment results. Aluminum alloys showed better corrosion protection in fully immersed conditions, while zinc alloys performed better in atmospheric and splash zones. Overall, these results aim to improve design of thermal spray coatings to protect carbon steel in marine environments. Full article
(This article belongs to the Special Issue Coatings Challenges in Harsh Environments)
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Review

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36 pages, 2388 KiB  
Review
A Review on the Electrodeposition of Aluminum and Aluminum Alloys in Ionic Liquids
by Kranthi Kumar Maniam and Shiladitya Paul
Coatings 2021, 11(1), 80; https://doi.org/10.3390/coatings11010080 - 12 Jan 2021
Cited by 41 | Viewed by 7979
Abstract
Aluminum plays an essential role as an excellent coating material in diversified applications due to its better corrosion resistance and physicochemical properties. Employing such a material as a coating on different metallic substrates such as carbon steel would benefit many industries such as [...] Read more.
Aluminum plays an essential role as an excellent coating material in diversified applications due to its better corrosion resistance and physicochemical properties. Employing such a material as a coating on different metallic substrates such as carbon steel would benefit many industries such as the automotive, aviation, shipbuilding, construction, electronics etc. Amongst the various available coating techniques, electrodeposition of aluminum (Al) Al alloys have gained significant attention in the last 10 years as a metallic protection coating for various commercial substrates and has become the industry’s choice owing to being lightweight, corrosion-resistant, and cost-effective. This paper shall provide a detailed review covering electrochemical deposition of Al and Al alloys using ionic liquids with various cations, anions, and additives, and reports on progress in development thus far. It shall also cover the challenges in the electrodepositing aluminum, its alloys on light weight metal substrates viz., magnesium (Mg), commercial substrates such as low carbon steel, spring steel, and their pretreatments. The factors that play an important role in electroplating on an industrial scale, along with future challenges, are discussed. Full article
(This article belongs to the Special Issue Coatings Challenges in Harsh Environments)
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